Oral pharmaceutical dispersion compositions

ABSTRACT

The invention provides an oral pharmaceutical composition, optionally in dose unit form, comprising a lipophilic drug substance in dispersion in a physiologically tolerable aqueous carrier, preferably an aqueous gel, wherein said drug substance contains a functional electrostatic group having a pKa value of from 2 to 10, characterised in that said aqueous carrier has a pH at least 0.3 below or above said pKa value, said pH being below said pKa where said group is acidic and above said pKa where said group is basic.

This invention relates to oral pharmaceutical compositions in the form of dispersions, preferably gelled aqueous emulsions, particularly gelled oil-in-water emulsions, preferably comprising a hydrophilic drug substance, but optionally a lipophilic or amphiphilic drug substance and to methods of treatment of a human subject therewith.

Many drug substances, i.e. the physiologically active components of pharmaceutical compositions, have an unpleasant taste and/or odour. Accordingly, any therapeutic or prophylactic dosage regime which involves the consumption of unpleasant tasting or nasty smelling dose units is inherently at risk of patient non-compliance.

Moreover, when the unit dose of a drug substance is large, the oral unit dosage forms, e.g. tablets or capsules, may likewise be large and so difficult for elderly or young patients to swallow and moreover may cause a gagging reaction even with healthy adults. Accordingly, any therapeutic or prophylactic dosage regime which involves the consumption of large numbers of dose units or numbers of large, difficult to swallow, dose units is inherently at risk of patient non-compliance.

For some drug substances it is possible to use a chewable tablet, a suckable lozenge, or a film that dissolves in the mouth as the vehicle for the drug substance. Nevertheless, this is not feasible where the drug substance has a bitter or unpleasant taste or where it is primarily intended to be taken up lower down the gastrointestinal tract.

We have previously found that drug substances may be administered without these problems when contained within a piece of soft, chewable, gelled oil-in-water emulsion. Lipophilic drugs may be dissolved in the lipid phase. Where the drug substance is a hydrophilic drug, this may be dissolved in an aqueous phase within said oil-in-water emulsion, i.e. as a gelled water-in-oil-in water emulsion (a “double emulsion”).

We have now surprisingly found that, rather than, or in addition to, dissolving the drug in the innermost phase of the emulsion (i.e. the lipophilic drug in the oil phase of an oil-in-water emulsion or the hydrophilic drug in the aqueous phase of a water-in-oil-in water emulsion) the drug substance may be dispersed as a solid, e.g. in particulate form, in whatever phase is most convenient. In this way a particularly high drug loading of the emulsion may be achieved thus reducing the need for the patient to consume multiple or oversized dosage units. Particularly preferably, the invention comprises dispersion of a hydrophilic drug in the lipid phase of a gelled oil-in-water emulsion, and more particularly a lipophilic drug dispersed in the continuous aqueous phase of a gelled oil-in-water emulsion.

This is especially useful when the drug substances to be administrated have a strong, unpleasant taste.

Thus viewed from one aspect the invention provides an oral pharmaceutical composition comprising a drug substance contained in a physiologically tolerable gelled oil-in-water emulsion, wherein said drug substance is a hydrophilic drug dispersed in the lipid phase or a lipophilic drug substance dispersed in a, preferably continuous, aqueous phase of the emulsion.

The gelled emulsions of the invention are preferably in soft, chewable form.

Hydrophilic drugs, i.e. those which may be dispersed in, but not fully dissolved in, the lipid phase include those characterised by their physicochemical properties in that they carry electrostatic charges (e.g. salts) and/or a substantial amount of polar functions such as hydroxyl, keto, phosphate, amino and/or sulphydryl groups. Examples of particular hydrophilic drug substances for use according to the invention include: pyroxidine, sulfamethoxazole, guanethidine monosulphate, leocovorin, lithium salt, naproxen sodium, bismuth subsalicylate, sodium acetazolamide, acetyl salicylic acid, aminophylline, amiodarone hydrochloride, ascorbic acid, atenolol, bendroflumethiazide, calcium folinate, captopril, cetrizine hydrochloride, chloramphenicol sodium succinate, chlorpheniramine maleate, chlorpromazine hydrochloride, cimetidine hydrochloride, ciprofloxacin hydrochloride, clindamycin hydrochloride, clonidine hydrochloride, codeine phosphate, cyclizine hydrochloride, cyclophosphamide, sodium dexamethasone phosphate, sodium dicloxacillin, dicyclomide hydrochloride, diltiazem hydrochloride, diphenhydramine hydrochloride, disopyramide phosphate, doxepin hydrochloride, enalapril maleate, erythromycin ethylsuccinate, flecanide acetate, fluphenazine hydrochloride, folic acid, granisteron hydrochloride, guaifenesin, haloperidol lactate, hydralazin hydrochloride, hydrochloroquine sulfate, hydromorphone hydrochloride, hydroxyzine hydrochloride, sodium indomethacin, isoniazid, isoprenaline hydrochloride, ketorolac trometamol, labetalol hydrochloride, lisinopril, lithium sulfate, mesoridazine benzylate, methadone hydrochloride, methylphenidate hydrochloride, methylprednisolone sodium succinate, metorprolol tartrate, metronidazole hydrochloride, metyldopa, mexiletine hydrochloride, molidone hydrochloride, morphine sulfate, naltrexone hydrochloride, neomycin sulfate, ondanstreon hydrochloride, orciprenaline sulfate, sodium oxacillin, oxybutynin chloride, oxycodone hydrochloride, paracetamol, penicillamine, pentoxifylline, petidine hydrochloride, sodium phenobarbital, potassium phenoxymethylpenicillin, phenylephrine hydrochloride, sodium phenytoin, potassium iodide, primaquine phosphate, procainamide hydrochloride, procarbazine hydrochloride, prochlorperazine maleate, promazine hydrochloride, promethazine hydrochloride, propranolol hydrochloride, pseudoephedrine hydrochloride, pyridostigmine bromide, pyridoxine hydrochloride, ranitidine hydrochloride, salbutamol sulfate, sodium ethacrynate, sotalol hydrochloride, sumatripan succinate, terbinafine hydrochloride, terbutaline sulfate, tetracycline hydrochloride, thioridazine hydrochloride, thiothixene hydrochloride, trifluoperazine hydrochloride, triprolidine hydrochloride, sodium valproate, vancomycin hydrochloride, vancomycin hydrochloride, verapamil hydrochloride, sodium warfarin.

Suitable doses for selected drugs are: sulfamethoxazole (200 mg), guanethidine monosulphate (10 mg), leucovorin (5 mg), lithium salt (300 mg), naproxen sodium (250 mg), bismuth subsalicylate (250 mg), guaifenesin, (200 mg), ketorolac trometamol (10 mg), cyclophosphamide (25 mg), phenoxymethylpenicillin (125 mg), Metronidazol (250 mg). Further suitable doses are given in the tables below.

In a further aspect the invention involves the dispersion of a lipophilic drug in the aqueous phase of an oil in water emulsion (i.e. the continuous phase) or a water-in-oil-in-water emulsion (i.e. the continuous aqueous phase and/or the discontinuous aqueous phase).

Thus viewed from a further aspect, the present invention provides an oral pharmaceutical composition comprising a drug substance contained in a physiologically tolerable gelled oil-in-water emulsion, wherein said drug substance is a lipophilic drug dispersed in an aqueous phase.

Suitable lipophilic drugs are well documented and include temazepam; diphenhydramine; zolpidem; triazolam; nitrazepam; testosterone; estradiol; progesterone; benzodiazepines; barbiturates; cyclosporine; insulin; calcitonin; dextromethorphan; pseudoephedrine; phenylpropanolamine; bromocryptine; apomorphine; selegiline; amitriptyline; dextroamphetamine; phentermine; mazindol; compazine; chlorpromazine; perphenazine; fluoxetine, buspirone; clemastine; chlorpheniramine; dexochlorpheniramine; astemizole; loratadine; paracetamol; ketoprofen; naproxen; and, particularly, ibuprofen.

The present invention involves the dispersion of a drug in a phase of an emulsion in which it is not fully soluble. The drug substance therefore remains in solid, e.g. crystalline form to some extent in the compositions, methods and uses of the invention.

In addition to a hydrophilic drug being dispersed in a lipid phase and/or a lipophilic drug being dispersed in an aqueous phase in the gelled compositions comprising oil-in-water emulsions of the invention, further drug/phase combinations may be present in the gelled compositions, whether by dispersion and/or dissolution. For example, the following compositions are envisaged:

-   -   Hydrophilic drug dispersed in lipid phase and hydrophilic drug         dissolved in aqueous phase.     -   Hydrophilic drug dispersed in lipid phase and lipophilic drug         dissolved in lipid phase.     -   Hydrophilic drug dispersed in lipid phase and lipophilic drug         dissolved in lipid phase and hydrophilic drug dissolved in         aqueous phase.     -   Hydrophilic drug dispersed in oil phase and lipophilic drug         dispersed in aqueous phase.     -   Lipophilic drug dispersed in aqueous phase and lipophilic drug         dissolved in lipid phase.     -   Lipophilic drug dispersed in aqueous phase and hydrophilic drug         dissolved in aqueous phase.     -   Lipophilic drug dispersed in aqueous phase and hydrophilic drug         dissolved in aqueous phase and lipophilic drug dissolved in         lipid phase.

In each case the hydrophilic drugs in the phases may be the same or different and the lipophilic drugs in the phases may be the same or different. Amphiphilic drugs may also be present.

In one aspect of the invention the compositions of the invention comprise a lipophilic drug dispersed in the continuous aqueous phase of an oil in water emulsion in the gelled emulsions of the invention.

In order to facilitate even dispersion throughout the phase containing it, the drug substance is preferably in particulate form. The optimal particle size for good dispersion and good mouthfeel of the resulting gelled emulsion varies depending on the nature of the drug and the composition of the phase in which it is dissolved, however suitable particle sizes (e.g. mode maximum particle dimension) are 0.5-25 μm, preferably 1-20 μm, particularly 2-15 μm.

Particularly preferably the compositions of the invention will contain two or more drugs, or even one or more lipophilic drugs in combination with one or more hydrophilic drugs, where the drugs are dispersed in the aqueous and oil phases of an emulsion respectively.

The compositions of the invention are preferably in dose unit form, and each dose until will typically contain 10% to 100%, preferably 50% to 100% of the recommended daily (or one-off) dose of the particular drug substance. Examples of recommended daily or one-off doses for some of the drug substances mentioned herein are set out in Table 1 below.

Where the human recipient is a child, the compositions according to the invention are especially suitable since they can readily and accurately be divided, for example by cutting with a blade, to provide the dosage required for the child's particular age or bodyweight/size. For this reason it is preferred to mark the dose unit (e.g. with surface markings such as a scale of bodyweight, height or age) or its packaging (e.g. the blister or blister cover of a blister-packed gelled emulsion) with indications showing where the gelled emulsion dose unit may be divided to yield a fragment containing the desired dosage.

TABLE 1 Typical daily or one-off drug doses Drug substance Dose per dose unit (mg) Ibuprofen 100-1500 (e.g. 200, 400, 600 and 800) Naproxen 250, 375 and 500 Ketoprofen 12.5-300 (e.g. 12.5, 50, 75, 100 and 200) Paracetamol 500-1000 Loratadine 10 Astemizole 10, 50 and 200 Dexochlorpheniramine 2-12 (e.g. 2, 4, 6 and 8) Chlorpheniramine  4 Clemastine 1 and 2 (as fumarate, 1.34 and 2.68) Diphenhydramine 25 and 50 Buspirone 5, 10, 15, and 30 Fluoxetine 5-90 (e.g. 10 and 20) Perphenazine 2, 4, 8 and 16 Chlorpromazine 10, 25, 50, 100 and 200 Prochlorperazine 5, 10 and 15 Mazindol 1, 2 and 3 Phentermine 8-40 (e.g. 8, 15 and 30) Dextroamphetamine 5, 10 and 15 Amitriptyline 10, 25, 50, 75, 100 and 150 Selegiline 1.25, 5 and 10 Apomorphine 5 and 10 Bromocryptine 2.5 to 40 (e.g. 2.5, 5, 10, 15) Phenylpropanolamine 25, 50, 75, 400 and 600 Pseudoephedrine 60 and 120 Dextromethorphan 30-600 (e.g. 30, 90, 400) Calcitonin 5, 30, 35, 75 and 150 Insulin Recommended daily dose Cyclosporine 25 and 100 Barbiturate (butabarbital) 30, 50 and 100 Benzodiazepine (e.g. temazepam, 0.25, 0.5, 1 and 2 triazolam and nitrazepam) Progesterone 100, 200 and 300 Estradiol (as estradiol valerinate) 0.5, 1 and 2 Testosterone (as testosterone 10 undecanoate) Nitrazepam 0.3, 1, 2.5, 5 and 10 Triazolam 0.125, 0.25 and 0.5 Zolpidem 5 and 10 Temazepam 7.5, 15, 22.5 and 30 Ergocalciferol 10-200 kIU (e.g. 30000 IU) Alphacalcidol 0.25, 0.5, 1 and 2 micrograms Calcitriol 0.25, 0.5, 1 and 2 micrograms The selegiline, apomorphine, insulin and calcitonin dose units are preferably dissolved in the mouth rather than chewed/swallowed.

TABLE 2 Drug substance Dose per dose unit (mg) Acetazolamide sodium 125 Acetyl salicylic acid  75 Aminophylline 100 Amiodarone hydrochloride 100 Ascorbic acid 25-100 Atenolol 25-100 Bendroflumethiazide 5-10 Calcium folinate 5-25 Captopril 12.5-100   Cetrizine hydrochlorid 2.5-10   Chloramphenicol sodium succinate 125 Chlorpheniramine maleate 2-12 Chlorpromazine hydrochloride 10-100 Cimetidine hydrochloride 100 Ciprofloxacin hydrochloride 100 Clindamycin hydrochloride 75-150 Clonidine hydrochloride 0.1-0.3  Codeine phosphate 15-60  Cyclizine hydrochloride 50-150 Cyclophosphamide 25-50  Dexamethasone sodium phosphate 0.25-6    Dicloxacillin sodium 125 Dicyclomide hydrochloride  20 Diltiazem hydrochloride 30-120 Diphenhydramine hydrochloride 12.5-50   Disopyramide phosphate 100 Doxepin hydrochloride 10-150 Enalapril maleate    2.5 Erythromycin ethylsuccinate 100 Flecanide acetate 50-150 Fluphenazine hydrochloride 1-10 Folic acid 0.4-1   Granisteron hydrochloride  1 Guafenesin 100 Haloperidol lactate 0.5-20   Hydralazin hydrochloride 10-100 Hydrochloroquine sulphate 200 Hydromorphone hydrochloride 1-8  Hydroxyzine hydrochloride 10-100 Indomethacin sodium 25-75  Isoniazid 50-100 Isoprenaline hydrochloride 10-15  Ketorolac trometamol  10 Labetalol hydrochloride 100 Lisinopril 2.5-40   Lithium sulphate 42-83  Mesoridazine bensylate 10-100 Methadone hydrochloride 5-40 Methylphenidate hydrochloride 5-20 Methylprednisolone sodium succinate 2-32 Metorprolol tartrate 50-100 Metronidazole hydrochloride 250 Metyldopa 125 Mexiletine hydrochloride 150 Molidone hydrochloride  5-100 Morphine sulphate 15-200 Naltrexone hydrochloride  50 Neomycin sulphate 125 Ondanstreon hydrochloride 4-8  Orciprenaline sulphate 10-20  Oxacillin sodium 250 Oxybutynin chloride  5 Oxycodone hydrochloride 5-80 Paracetamol 80-160 Penicillamine 125 Pentoxifylline 400 Petidine hydrochloride 50-100 Phenobarbital sodium 15-100 Phenoxymethylpenicillin potassium 125 Phenylephrine hydrochloride  10 Phenytoin sodium 50-100 Potassium iodide 130 Primaquine phosphate  15 Procainamide hydrochloride 250 Procarbazine hydrochloride  50 Prochlorperazine maleate 5-30 Promazine hydrochloride 25-50  Promethazine hydrochloride 12.5-50   Propranolol hydrochloride 10-160 Pseudoephedrine hydrochloride 30-120 Pyridostigmine bromide 60-180 Pyridoxine hydrochloride 10-200 Ranitidine hydrochloride 75-150 Salbutamol sulphate 2-8  Sodium ethacrynate 25-50  Sotalol hydrochloride 80-160 Sumatripan succinate 25-50  Terbinafine hydrochloride 250 Terbutaline sulphate 2.5-5   Tetracycline hydrochloride 125 Thioridazine hydrochloride 10-150 Thiothixene hydrochloride 1-20 Trifluoperazine hydrochloride 1-10 Triprolidine hydrochloride    2.5 Valproate sodium 125 Vancomycin hydrochloride 125 Verapamil hydrochloride 40-120 Warfarin sodium 1-10

By dispersing the drug substance in an emulsion phase, a greater loading of the drug can be obtained than if it had to be dissolved. In particular, the present invention can dramatically increase the loading capacity of hydrophilic drugs and/or lipophilic drugs in gelled oil-in-water emulsion. Moreover, by administering drugs in the gelled emulsions of the invention, the unpleasant taste of many drug substances can be masked, thus improving patient compliance. The gelled emulsion dosage form also protects the gastrointestinal tract from the irritation which may be experienced from administration of certain drugs, e.g. NSAIDs.

By drug substance is meant a substance having a desirable therapeutic or prophylactic effect other than as a nutrient, i.e. substances of the type for which regulatory approval as a drug is required in for example the US or the European Union. Less preferably, the drug substance may be a vitamin which classifies as a drug substance for regulatory purposes, e.g. vitamin A, K or D (e.g. ergocalciferol, alphacalcidol and calcitriol). Vitamins, including these, as well as mineral and/or herbs may of course be included in the compositions in addition to non-vitamin drug substances.

By amphiphilic drug substance is meant a drug substance that will distribute at the oil droplet surface. In the single emulsion of the present invention the amphiphilic drug substance is mixed with the oil phase and in the double emulsion of the present invention the amphiphilic drug substance is mixed either with the oil or with the discontinuous aqueous phase of the double emulsion.

Examples of categories of suitable drug substances for use according to the invention include: analgesics; anti-inflammatories; anticancer agents; cardiovascular agents; biological agents; antiallergy agents (e.g. antihistamines); decongestants; antinausea agents, drugs affecting gastrointestinal function, drugs acting on the blood and blood-forming organs, drugs affecting renal and cardiovascular function, antifungal agents, urological agents, hormones, antimicrobial agents, antiepileptical agents, psycholeptical agents, antipsychotic agents, psychoanaleptical agents, anticholinesterase agents, drugs acting on the respiration organs and drugs acting on the eye.

Viewed from a further aspect the invention provides a pharmaceutical composition, comprising a drug substance contained in a physiologically tolerable gelled oil-in-water emulsion, wherein said drug substance is a hydrophilic drug dispersed in an oil phase and/or a lipophilic drug dispersed in a, preferably continuous, aqueous phase of the emulsion for use in medicine.

Viewed from a further aspect the invention provides a pharmaceutical composition, comprising a drug substance contained in a physiologically tolerable gelled oil-in-water emulsion, wherein said drug substance is a hydrophilic drug dispersed in an oil phase and/or a lipophilic drug dispersed in a, preferably continuous, aqueous phase of the emulsion for use in the treatment of retroviral infection, tuberculosis, pneumonia, malaria, leprosy, erectile dysfunction, cancer, cardiovascular diseases, hypertension, pain, bacterial infection, vitamin deficiency or inflammation.

Viewed from a still further aspect the invention provides the use of a drug substance for the manufacture of a medicament for use by oral administration in the treatment of retroviral infection, tuberculosis, pneumonia, malaria, leprosy, erectile dysfunction, cancer, cardiovascular diseases, hypertension, pain, bacterial infection, vitamin deficiency or inflammation, wherein said drug substance is contained in a physiologically tolerable gelled oil-in-water emulsion and is a hydrophilic drug dispersed in an oil phase and/or a lipophilic drug dispersed in a, preferably continuous, aqueous phase of the emulsion.

Viewed from a still further aspect the invention provides a method of treatment of a human subject to combat retroviral infection, tuberculosis, pneumonia, malaria, leprosy, erectile dysfunction, cancer, cardiovascular diseases, hypertension, pain, bacterial infection, vitamin deficiency or inflammation, which method comprises orally administering to said subject an effective amount of a pharmaceutical composition comprising a drug substance contained in a physiologically tolerable gelled oil-in-water emulsion, wherein said drug substance is a hydrophilic drug dispersed in an oil phase and/or a lipophilic drug dispersed in a, preferably continuous, aqueous phase of the emulsion.

The drug substance may typically be included in the compositions of the invention at 10% to 100% of its normal oral daily dose, especially 50% to 100%.

Besides the drug substance, the compositions of the invention may contain further components such as nutrients, e.g. lipids, (especially triglycerides and phospholipids, typically of plant or marine animal origin), vitamins, minerals, and folic acid, pH modifiers, viscosity modifiers, flavours, aromas, sweeteners, colorants, antioxidants, etc.

The gelled emulsion compositions of the invention will preferably be in dose unit form, with each dose unit having a weight of 50 to 3000 mg, especially 100 to 2000 mg, particularly 100 to 1500 mg, more particularly 400 to 1500 mg, more especially 400 to 1000 mg.

The composition of the invention will preferably be uncoated, i.e. not within a capsule or shell-coating. Accordingly, to avoid water loss during storage, the dose units will conveniently be individually packaged, e.g. in foil wrappers or in the blisters of a blister pack.

The dose units of the gelled emulsion may be formed for example by moulding, extrusion or cutting or the like. For adult use, the dose units are preferably in tablet or lozenge form; however for child use they may conveniently be presented in child-friendly form, e.g. geometric shapes such as rods, strips and tubes, or animal, doll, or vehicle shapes, for example the shape of a popular cartoon character.

The oil phase of the oil-in-water emulsion may be any physiologically tolerable lipid, e.g. fatty acid esters such as triglycerides and phospholipids, for example plant or animal oils, especially plant and marine animal oils. Particularly preferably an oil is used which is high in omega-3, omega-6 or omega-9 essential fatty acids, especially omega-3 essential fatty acids, more especially EPA and DHA. In this way the oil phase itself is a highly bioavailable source of nutrient lipids.

Examples of omega-3 acids include a-linolenic acid (ALA), stearidonic acid (SDA), eicosatrienoic acid (ETE), eicosatetraenoic acid (ETA), eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA), docosahexaenoic acid (DHA), tetracosapentaenoic acid and tetracosahexaenoic acid. Examples of omega-6 acids include linoleic acid, gamma-linolenic acid, eicosadienoic acid, dihomo-gamma-linolenic acid (DGLA), arachidonic acid (AA), docosadienoic acid, adrenic acid, docosapentaenoic acid, and calendic acid. Examples of omega-9 acids include oleic acid, eicosenoic acid, mead acid, erucic acid and nervonic acid.

It is particularly preferred that the compositions according to the invention contain a citrus flavour (e.g. orange or lemon oil) in order to mask any remaining oil taste on chewing. It is also particularly preferred that the compositions according to the invention contain xylitol, e.g. as 0.5 to 50% wt., preferably 1 to 40% wt., e.g. 15 to 40% wt., in order to mask both taste and mouth feel. These may be in the aqueous phase or the oil phase (e.g. as a water-in-oil-in water emulsion), or both; however inclusion in the aqueous phase will generally be sufficient.

Other than the drug substance, the essential fatty acids may form part or the whole of the oil phase in the gelled emulsion, preferably at least 10% wt, more especially at least 50% wt, particularly at least 80% wt. of that phase. They may be used as single compounds or as compound mixtures, e.g. plant or marine oils.

The oil phase of the oil-in-water emulsion may also contain solubilisers in order to increase the solubility of the drug substance in the oil phase. Suitable solubilisers would be known to a person skilled in the art and include Chremophor EL™, castor oil, Tween 80™, Solutol™ HS15, Lutrol™ and Olestra.

The aqueous phase of the gelled emulsion will contain water and a physiologically tolerable gelling agent, e.g. a hydrocolloid such as gelatin, alginate, carrageenan or a pectin. Such gelling agents and their gel-forming properties are well known. See for example Phillips G O and Williams P A (Eds.) Handbook of hydrocolloids, Woodhead Publishing, Cambridge (2000). The use of gelatin is especially preferred. Besides water and the gelling agent, the aqueous phase of the gelled emulsion may contain other water-soluble components, e.g. vitamins, minerals, pH modifiers, viscosity modifiers, antioxidants, colorants, flavours, water-soluble drug substances, etc. as desired.

The weight ratio of the lipid phase to the aqueous phase in the gelled emulsions is preferably 1:19 to 3:1, especially 35:65 to 1:1, particularly 2:3 to 1:1.

Emulsion formation may be effected by conventional techniques; however emulsification under a non-oxidising gas, e.g. nitrogen, is preferred. Likewise, the components of the emulsion are preferably degassed before emulsification and handling and packaging of the set emulsion is preferably performed under such a gas.

The gelled emulsions of and used according to the invention may be produced as described in WO 2007/085835 and WO 2007/085840 and PCT/GB2009/002404 and PCT/GB2009/002406 (copies of which are annexed to the description of this application as Annexes A and B) the contents of which are hereby incorporated by reference.

The gelled emulsions may if desired be more than biphasic. Thus a water-in-oil emulsion may be emulsified with an aqueous gelling agent phase to produce a water-in-oil-in-water double emulsion, or two oil-in-water emulsions with different oil phases may be combined and intimately mixed before gelling onset.

We have also found that in the case of lipophilic drug substances carrying a functional electrostatic group having a pKa value of 2 to 10, more especially 4 to 10, particularly 4.5 to 9, the composition may be presented in the form of an aqueous dispersion of the drug substance and having an aqueous phase pH which is at least 0.3, preferably at least 0.5, more preferably at least 1, for example up to 2.5, preferably up to more preferably up to 1.8, below or above the pKa value of the electrostatic group, the pH being below the pKa value where the electrostatic group is acidic (e.g. a carboxyl group) and above the pKa value where the electrostatic group is basic (e.g. an amine group). Where the drug substance contains two or more functional electrostatic groups, the pH is preferably below or above the lowest acid group pKa or above the highest basic group pKa by these values. In this way, not only is it possible to achieve a high loading of the lipophilic drug compound into the oral pharmaceutical composition but also the unpleasant mouthfeel that otherwise arises with aqueous dispersions of such drugs is masked. If desired, a strong flavouring agent may also be included to further mask mouthfeel, e.g. a citrus fruit flavour such as grapefruit for acidic drugs.

Thus viewed from a further aspect the invention provides an oral pharmaceutical composition, optionally in dose unit form, comprising a lipophilic drug substance in dispersion in a physiologically tolerable aqueous carrier, preferably an aqueous gel, wherein said drug substance contains a functional electrostatic group having a pKa value of from 2 to 10, preferably 4 to 9, especially 4.5 to 8.5, characterised in that said aqueous carrier has a pH at least 0.3, preferably at least 0.5, more preferably at least 1 below or above said pKa value, said pH being below said pKa where said group is acidic and above said pKa where said group is basic.

pH and pKa values as referred to herein are preferably as measured at ambient temperature, typically and preferably 21° C.

The aqueous dispersions of the invention may be in any suitable form, e.g. gels, suspensions, viscous liquids (e.g. syrups) or simple dispersions.

Preferably however they are aqueous gels. The gelling agents used may be any physiologically tolerable agents, preferably gelling agents as described elsewhere herein.

The lipophilic drug substance used in the dispersions of the invention may be any lipophilic drug substances having a functional group with a pKa in the appropriate range; preferably however it is an NSAID, particularly ibuprofen.

Where ibuprofen is used, the pH of the aqueous carrier is preferably about 4-4.5 as the pKa of the said group in ibuprofen is about 5. Using an aqueous carrier with a pH of 4-4.5 allows the extremely astringent mouthfeel of ibuprofen to be masked and reduces the solubility of ibuprofen in the aqueous carrier.

The desired pH of the aqueous carrier may be achieved by the use of well known physiologically tolerable acids, bases and buffers, e.g. using fruit acids such as citric acid.

Viewed from a further aspect the invention provides a lipophilic drug substance having a functional electrostatic group having a pKa of 2 to 10 for use in a method of treatment of a human or non human animal (especially a mammal) subject to combat a condition responsive thereto, which method comprises orally administering to said subject an oral pharmaceutical composition comprising said drug substance dispersed in an aqueous carrier having a pH at least 0.3, preferably at least 0.5, more preferably at least 1 below or above said pKa value, said pH being below said pKa where said group is acidic and above said pKa where said group is basic.

Viewed from a further aspect the invention provides the use of a lipophilic drug substance having a functional electrostatic group having a pKa of 2 to 10 for the manufacture of an oral pharmaceutical composition for use by oral administration in a method of treatment of a human or nonhuman animal subject to combat a condition responsive to said drug substance, said composition comprising said drug substance in dispersion in a physiologically tolerable aqueous carrier, preferably an aqueous gel, characterised in that said aqueous carrier has a pH at least 0.3, preferably at least 0.5, more preferably at least 1 below or above said pKa value, said pH being below said pKa where said group is acidic and above said pKa where said group is basic.

Viewed from a still further aspect the invention provides a method of treatment of a human or nonhuman animal subject by oral administration thereto of an effective amount of an oral pharmaceutical composition comprising a lipophilic drug substance having a functional electrostatic group having a pKa of 2 to 10 to combat a condition responsive to said drug substance, said composition comprising said drug substance in dispersion in a physiologically tolerable aqueous carrier, preferably an aqueous gel, characterised in that said aqueous carrier has a pH at least 0.3, preferably at least 0.5, more preferably at least 1 below or above said pKa value, said pH being below said pKa where said group is acidic and above said pKa where said group is basic.

The invention will now be illustrated further with reference to the following non-limiting Examples.

EXAMPLE 1 Drug-Free Composition

An aqueous phase is formed from the following ingredients:

Gelatin 7.5% wt Xylitol 36% wt Sorbitol 14% wt 50% Citric acid 1% wt Lemon flavour 0.15% wt Water ad 100% wt

Sunflower oil (or alternatively an omega-3 ester (Omacor®)) is emulsified with the aqueous phase in a weight ratio of 45:55 and the emulsion is poured in aliquots of 1.5 g into elongate moulds lined with a metal/plastics laminate blister tray and allowed to set. The blister tray is thermally sealed with a metal/plastics foil cover sheet.

EXAMPLE 2 Drug-Containing Compositions

The drugs listed in Table 1 above are dissolved in the aqueous phase and dispersed in the oil phase used in Example 1 at the concentrations per dose unit set out in Table 1 before emulsions are produced, poured and allowed to set as in Example 1. The set-gel dosage units are packaged as in Example 1.

For drug concentrations below 100 mg per dose unit, the dose units are conveniently 250, 500 or 750 mg. For concentrations above 100 mg per dose unit, the dose units are conveniently 500, 1000, 1500, 2000, 2500 or 3000 mg.

EXAMPLE 3 Components

Gelatin 84 mg Gum arabicum 55.5 mg Sorbitol 155 mg Xylitol 360 mg Citric acid 9 mg Flavour 18 mg Colour 10.5 mg oil 0-600 mg Sulfamethoxazole 200 mg Trimethoprim 40 mg Water to 1500 mg

The oil(s) and sulfamethoxazole and trimethoprim are emulsified with the aqueous phase and the emulsion is poured in aliquots of 1.5 g into elongate moulds lined with a metal/plastics laminate blister tray and allowed to set. The blister tray is thermally sealed with a metal/plastics foil cover sheet

EXAMPLE 4 Components

Gelatin 84 mg Gum arabicum 55.5 mg Sorbitol 155 mg Xylitol 360 mg Citric acid 9 mg Flavour 18 mg Colour 10.5 mg Oil 0-600 mg Naltrexone 50 mg Water to 1500 mg

The oil(s) and naltrexone are emulsified with the aqueous phase and the emulsion is poured in aliquots of 1.5 g into elongate moulds lined with a metal/plastics laminate blister tray and allowed to set. The blister tray is thermally sealed with a metal/plastics foil cover sheet

EXAMPLE 5 Components

Gelatin 84 mg Gum arabicum 55.5 mg Sorbitol 155 mg Xylitol 360 mg Citric acid 9 mg Flavour 18 mg Colour 10.5 mg Oil 0-600 mg Promethazine 12.5 mg Water to 1500 mg

The oil(s) and promethazine are emulsified with the aqueous phase and the emulsion is poured in aliquots of 1.5 g into elongate moulds lined with a metal/plastics laminate blister tray and allowed to set. The blister tray is thermally sealed with a metal/plastics foil cover sheet

EXAMPLE 6 Components

Gelatin 84 mg Gum arabicum 55.5 mg Sorbitol 155 mg Xylitol 360 mg Citric acid 9 mg Flavour 18 mg Colour 10.5 mg Oil 0-600 mg leucovorin 10 mg Water to 1500 mg

The oil(s) and leucovorin are emulsified with the aqueous phase and the emulsion is poured in aliquots of 1.5 g into elongate moulds lined with a metal/plastics laminate blister tray and allowed to set. The blister tray is thermally sealed with a metal/plastics foil cover sheet

EXAMPLE 7 Components

Gelatin 84 mg Gum arabicum 55.5 mg Sorbitol 155 mg Xylitol 360 mg Citric acid 9 mg Flavour 18 mg Colour 10.5 mg Oil 0-600 mg Atenolol 50 mg Water to 1500 mg

The oil(s) and atenolol are emulsified with the aqueous phase and the emulsion is poured in aliquots of 1.5 g into elongate moulds lined with a metal/plastics laminate blister tray and allowed to set. The blister tray is thermally sealed with a metal/plastics foil cover sheet

EXAMPLE 8 Components

Gelatin 84 mg Gum arabicum 55.5 mg Sorbitol 155 mg Xylitol 360 mg Citric acid 9 mg Flavour 18 mg Colour 10.5 mg Oil 0-600 mg Sumatriptan 25 mg Water to 1500 mg

The oil(s) and sumatriptan are emulsified with the aqueous phase and the emulsion is poured in aliquots of 1.5 g into elongate moulds lined with a metal/plastics laminate blister tray and allowed to set. The blister tray is thermally sealed with a metal/plastics foil cover sheet

EXAMPLE 9 Gelled Ibuprofen Dispersions

Crystalline ibuprofen is dispersed at 10% wt concentration in an aqueous solution comprising the ingredients listed below and the dispersion is poured into elongate molds as described in the previous example, allowed to set and sealed.

Contents:

Ingredient Content (% wt) Water 27.45 Gelatin 11.49 Sorbitol 18.50 Xylitol 30.85 Sodium saccharin 0.0158 Sodium cyclamate 0.1573 Citric acid 0.53 Ibuprofen 90 10.00 Total 100.00 

1. An oral pharmaceutical composition, optionally in dose unit form, comprising a lipophilic drug substance in dispersion in a physiologically tolerable aqueous carrier, preferably an aqueous gel, wherein said drug substance contains a functional electrostatic group having a pKa value of from 2 to 10, characterised in that said aqueous carrier has a pH at least 0.3 below or above said pKa value, said pH being below said pKa where said group is acidic and above said pKa where said group is basic.
 2. A composition as claimed in claim 1 wherein said carrier is an aqueous gel.
 3. A composition as claimed in either of claims 1 and 2 wherein said drug substance is an NSAID.
 4. A composition as claimed in claim 3 wherein said drug substance is ibuprofen.
 5. A composition as claimed in claim 4 wherein the pH of said carrier is in the range 4 to 4.5.
 6. An oral pharmaceutical composition comprising a drug substance contained in a physiologically tolerable gelled oil-in-water emulsion, wherein said drug substance is a hydrophilic drug dispersed in the lipid phase or a lipophilic drug substance dispersed in a, preferably continuous, aqueous phase of the emulsion.
 7. A pharmaceutical composition, comprising a drug substance contained in a physiologically tolerable gelled oil-in-water emulsion, wherein said drug substance is a hydrophilic drug dispersed in an oil phase and/or a lipophilic drug dispersed in a, preferably continuous, aqueous phase of the emulsion for use in medicine.
 8. A pharmaceutical composition, comprising a drug substance contained in a physiologically tolerable gelled oil-in-water emulsion, wherein said drug substance is a hydrophilic drug dispersed in an oil phase and/or a lipophilic drug dispersed in a, preferably continuous, aqueous phase of the emulsion, for use treatment of retroviral infection, tuberculosis, pneumonia, malaria, leprosy, erectile dysfunction, cancer, cardiovascular diseases, hypertension, pain, bacterial infection, vitamin deficiency or inflammation.
 9. A lipophilic drug substance having a functional electrostatic group having a pKa of 2 to 10 for use in a method of treatment of a human or non human animal subject to combat a condition responsive thereto, which method comprises orally administering to said subject an oral pharmaceutical composition comprising said drug substance dispersed in an aqueous carrier having a pH at least 0.3 below or above said pKa value, said pH being below said pKa where said group is acidic and above said pKa where said group is basic.
 10. The use of a lipophilic drug substance having a functional electrostatic group having a pKa of 2 to 10 for the manufacture of an oral pharmaceutical composition for use by oral administration in a method of treatment of a human or nonhuman animal subject to combat a condition responsive to said drug substance, said composition comprising said drug substance in dispersion in a physiologically tolerable aqueous carrier, preferably an aqueous gel, characterised in that said aqueous carrier has a pH at least 0.3 below or above said pKa value, said pH being below said pKa where said group is acidic and above said pKa where said group is basic.
 11. A method of treatment of a human or nonhuman animal subject by oral administration thereto of an effective amount of an oral pharmaceutical composition comprising a lipophilic drug substance having a functional electrostatic group having a pKa of 2 to 10 to combat a condition responsive to said drug substance, said composition comprising said drug substance in dispersion in a physiologically tolerable aqueous carrier, preferably an aqueous gel, characterised in that said aqueous carrier has a pH at least 0.3 below or above said pKa value, said pH being below said pKa where said group is acidic and above said pKa where said group is basic.
 12. Use of a drug substance contained in a physiologically tolerable gelled oil-in-water emulsion for the manufacture of a medicament for use by oral administration in the treatment of retroviral infection, tuberculosis, pneumonia, malaria, leprosy, erectile dysfunction, cancer, cardiovascular diseases, hypertension, pain, bacterial infection, vitamin deficiency or inflammation, wherein said drug substance is a hydrophilic drug dispersed in an oil phase and/or a lipophilic drug dispersed in a, preferably continuous, aqueous phase of the emulsion.
 13. A method of treatment of a human subject to combat retroviral infection, tuberculosis, pneumonia, malaria, leprosy, erectile dysfunction, cancer, cardiovascular diseases, hypertension, pain, bacterial infection, vitamin deficiency or inflammation, which method comprises orally administering to said subject an effective amount of a pharmaceutical composition, comprising a drug substance contained in a physiologically tolerable gelled oil-in-water emulsion, wherein said drug substance is a hydrophilic drug dispersed in an oil phase and/or a lipophilic drug dispersed in a, preferably continuous, aqueous phase of the emulsion. 